One plane and smoke sims, no Photoshop just Cycles render results. The terrain was generated with a combination of A.N.T. Landscape and displacement. Material is also procedural. Erosion generated with an add-on I am working on (running on GPU for extremely fast simulation).
Checkout more here 1, here 2, here 3, and here 4
I featured you on BlenderNation, have a great weekend!
This is really amazing work! 
At first glance it seems like something created from real world heightmaps, or made with one of those terrain generator softwares.
The fact that it is basically procedural inside Blender is mind blowing! 
And those beautiful erosions! 
I’m really interested in your plugin!
This is amazing!!! Thank you Bart! 
Thanks a lot!!! 
I really need to do a tutorial when I get some time one of these days on the procedural side of the project! But the erosion is done by converting procedural noise to image height maps and running water simulation (there really is no other way unfortunately). However, all is done within Blender!
If you want to try the plugin the old version is here, please keep in mind that it is very very beta.
this is crazy…
Excellent Job
thanks!!!
Great work, congrats.
